The present invention relates to a vehicle occupant restraining system for protecting, in the event of a vehicle collision, the occupant against great impacts by the collision. More particularly, the invention relates to a vehicle occupant restraining system including air bags and seat belts.
FIG. 13 is a block diagram showing a conventional vehicle occupant restraining system disclosed in Unexamined Japanese Patent Publication 6-206514. In FIG. 13, reference numeral 101 is an occupant; 102 is an air bag; 110 is a collision sensor for detecting a vehicle collision; 111 is an occupant position sensor for detecting a distance from an air bag storage position to the occupant 101; 112 is a gas source for supplying gas to the air bag 102 to inflate or expand the same; 113 is a gas-amount setting circuit for setting an amount of gas to be supplied to the air bag 102; and 114 is a gas-amount control circuit for controlling an amount of gas to be supplied to the air bag 102.
The operations of the conventional vehicle occupant restraining system before and after a vehicle collision occurs will be described with reference to a flow chart shown in FIGS. 14A and FIG. 14B. FIG. 14A is a flow chart showing the operations of the circuitry including the occupant position sensor 111 and the gas-amount setting circuit 113 in the prior occupant restraining system shown in FIG. 13. The circuitry repeats the operations of steps S101 and S102 at fixed periods independently of the operations of other circuits. In the step S101, the occupant position sensor 111 detects a distance from the storing position of the air bag 102 to the occupant 101. In the steps S102, the gas-amount setting circuit 113 determines an amount of gas for inflating the air bag 102 on the basis of a position of the occupant 101, and stores (sets) the result of the determining.
FIG. 14B is a flow chart showing the operation of the vehicle occupant restraining system when a vehicle collides with an obstacle, for example. In step S103 the collision sensor 110 detects a vehicle collision, and in step S104 the gas-amount control circuit 114 causes the gas source 112 to supply to the air bag 102 an amount of gas that is set, at that time, by the gas-amount setting circuit 113. In this way, gas is supplied to the air bag 102, and the air bag 102 is inflated to protect the occupant 101 from great impacts caused by the collision.
Usually, when the occupant notices and recognizes an impending vehicle collision in advance, he will take some action for the collision; perhaps he will get stiff. When he inattentively drives the vehicle and fails to notice the pressing vehicle collision, he cannot take any action for the collision, and is merely restrained by the air bag and the seat belt, and he receives great impacts. In an extreme case, only his head is forcibly pushed forward while his chest is fixed by the seat belt, and large load exerts on his neck, for example. In this case, the parts of the human body that must first be guarded from the large load are the head and the neck.
The occupant restraining system operates as just mentioned, and hence, it can change its control mode depending on an occupant position. However, the system cannot determine as to whether or not the occupant was aware of and recognized the impeding vehicle collision. In a case where a vehicle clashes into an obstacle in a state that the occupant inattentively fails to notice and recognize the collision, he receives great impacts without any action for the collision by the occupant. Therefore, only his head is forcibly pushed forward and large load exerts on his neck.